178 MYCOLOGY 



Suborder Hemibasidii. — The conidiophore, or more correctly the 

 basidium, arises from the chlamydospore and bears an indetinite 

 and usually large number of basidiospores. All cells of the mycelium 

 and the spores, as far as known, are unicellular. The position of this 

 suborder in the family tree of the fungi is uncertain. The majority 

 of the funguses are strictly parasitic on the higher plants, and their 

 mycelia live in the tissues of the same, mostly as intercellular parasites, 

 certain hyphae known as haustoria penetrating the interior of the host 

 cells. Infection of the host takes place, as a rule, very early and in 

 some cases at the time of seed formation, so that the parasitic mycelium 

 keeps pace with the growth of the host plants and at definite times and 

 places, such as anthers, ovaries and the like, which are mostly de- 

 formed, the spore-bearing portion of the fungous parasite appears. 

 The spores, which are formed in such places, are known as chlamydo- 

 spores, and the mass of spores and diseased host parts are mostly 

 black and soot-like. The chlamydospores give rise to a promycelium, 

 which cuts off basidiospores. The basidiospores give rise either to 

 conidiospores, or they infect some host plant, if deposited upon it at 

 the susceptible time. Brefeld first suggested the name Hemibasidii for 

 the UsTiLAGiNACE^ and Tilletiace^ which he considered as repre- 

 senting the link connecting the lower fungi and the true BASIDIO- 

 MYCETALES. Two famiUes are recognized by mycologists, viz., 



USTILAGINACE^ and TlLLETIACE^. 



Family i. Ustilaginace^e. — ^The fungi of this family are all para- 

 sitic. They can be recognized readily by the outbreaks of dusty 

 material that they produce on certain parts of their hosts, when they 

 reach their reproductive stage. An important genus, Ustilago, the 

 type genus of the family, derives its name from ustio, a burning. The 

 smut of wheat is called locally in England "bunt ear," "black ball," 

 " dust brand" and " chimney sweeper." All of these names are indica- 

 tive of the sooty-black character of the spores. There are two chief 

 phases in the development of a smut fungus, the mycehal phase and 

 the spore phase. The hyphae of the mycelium mostly push between 

 the cells through the intercellular spaces and form short special branches, 

 or haustoria, which enter the host cells and absorb from them nutritive 

 material. The mycelium may be locahzed, or it may be spread gen- 

 erally throughout the host. Where the mycelium gains entrance to 

 the host through the germinating seeds, it remains in the vegetative 



